Monarch
among the misconceptionsIt's
no accident that viceroy butterflies look like monarchs. According to
a scientific fable that survived almost 100 years, monarchs taste lousy
because they eat toxin-rich milkweed, so birds learned to avoid them.
Viceroys evolved to have a similar appearance because birds avoided eating
viceroys that looked like monarchs.

The fable was considered
a classic example of evolution at work
-- of how organisms change to suit their environment.

This so-called
"Batesian" mimicry involves a model, the monarch, and a mimic, the viceroy.
It stands to reason that a vulnerable butterfly would evolve to look like
something that was immune to a major predator.

Eventually,
the pretty theory was skewered by some ugly facts. Standing to reason
is not the same thing as truth, and when entomologists ran the experiment,
they found Batesian mimicry was not involved. In fact, the viceroy was
as unpalatable as the monarch, at least to red-wing blackbirds. After
eating viceroy abdomens, the birds often shook their heads, guzzled water,
or acted agitated -- all indications that the viceroy tasted, well, like
a big bad bug.

In all, the birds
totally ate only 41 percent of viceroys, compared with about 45 percent
of monarchs and 98 percent of controls.

But the mimicry
hypothesis was not totally misplaced. In the "what's-in-it-for-me?" calculus
that is ecology, the situation may actually represent Mullerian, not Batesian,
mimicry. Both viceroys and monarchs benefit from the similarity in appearance
-- it's a more efficient way to "teach" predators that both species taste
gross (see "The Viceroy Butterfly..." in the bibliography).

While we're on
the subject of bogus biology, you do know Charles Darwin devised his theory
of evolution while studying finches at the Galapagos Islands... Wrong
again!